Semiconductor device including vertical routing structure and method for manufacturing the same

ABSTRACT

A method includes forming a transistor having source and drain regions. The following are formed on the source/drain region: a first via, a first metal layer extending along a first direction on the first via, a second via overlapping the first via on the first metal layer, and a second metal extending along a second direction different from the first direction on the second via; and the following are formed on the drain/source region: a third via, a third metal layer on the third via, a fourth via overlapping the third via over the third metal layer, and a controlled device at a same height level as the second metal layer on the third metal layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/941,716 filed Mar. 30, 2018, which claims priority to U.S.Provisional Patent Application 62/586,726 filed on Nov. 15, 2017, theentire disclosure of each of which is incorporated herein by reference.

TECHNICAL FIELD

The disclosure relates to a semiconductor device and a method ofmanufacturing the same. More specifically, the disclosure relates to asemiconductor device having a vertical routing structure and designed bya strategy provided by the vertical routing structure of the device, anda method of manufacturing the same.

BACKGROUND

Along with the increased demand of high density integrated circuit forminiaturized devices such as portable devices or for more powerfulcomputing capability, high aspect ratio devices are developed. Althoughthe substrate surface area occupied by a high aspect ratio device isreduced compared to a low aspect ratio thin film device, the componentsof the control circuit for the high aspect ratio device still scatterover the surface of the substrate. For a device controlled by multiplecontrolling devices, for example, controlling multiple voltage levels ofa source of a transistor so as to achieve a sophisticated control of adrain of the device, the multiple controlling devices would occupy alarge surface area of the substrate. Thus, there is a demand for aversatile device that can enhance the controllability while efficientlyreducing the substrate surface area occupied by the device and thecontrolling devices controlling the device.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 shows a cross-sectional view of a semiconductor device cuttingalong the x direction or a source-to-drain direction, according to anembodiment of the present disclosure.

FIG. 2(a) shows a top plan view of the semiconductor device in FIG. 1,and FIGS. 2(b) and 2(c) show alternative embodiments of FIG. 2(a).

FIG. 3, 4, 5, 6, 7, 8(a) or 8(b), 9(a) or 9(b), and 10(a) or 10(b) showsequential manufacturing operations of forming a portion of thesemiconductor device in FIG. 1, according to embodiments of the presentdisclosure.

FIGS. 11, 12, 13, 14, 15, 16, and 17 show sequential manufacturingoperations of forming the remaining portion of the semiconductor devicein FIG. 1, according to embodiments of the present disclosure.

FIG. 18 shows a cross-sectional view of a semiconductor device,according to another embodiment of the present disclosure.

FIG. 19 shows a cross-sectional view of a semiconductor device,according to another embodiment of the present disclosure.

FIG. 20 shows a method of forming the semiconductor device in FIG. 1,according to embodiments of the present disclosure.

FIG. 21 shows a cross-sectional view of a semiconductor device,according to an embodiment of the present disclosure.

FIGS. 22, 23, 24, 25, 26, 27, 28, and 29 show sequential manufacturingoperations of forming a portion of the semiconductor device in FIG. 21,according to embodiments of the present disclosure.

FIGS. 30, 31, 32, 33, 34, and 35 show sequential manufacturingoperations of forming the remaining portion of the semiconductor devicein FIG. 21, according to embodiments of the present disclosure.

FIG. 36 shows a method of forming the semiconductor device in FIG. 21,according to embodiments of the present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“being made of” may mean either “comprising” or “consisting of.” In thepresent disclosure, a phrase “one of A, B and C” means “A, B and/or C”(A, B, C, A and B, A and C, B and C, or A, B and C), and does not meanone element from A, one element from B and one element from C, unlessotherwise described.

FIG. 1 shows a semiconductor device cutting along the x direction or asource-to-drain direction, according to an embodiment of the presentdisclosure. In some embodiments, the semiconductor device includes atransistor portion. In some embodiments, the transistor portion includesa planar transistor (FET). In some embodiments, the transistor portionincludes a surrounding gate transistor or a FinFET. In the currenttechnology node, a FinFET with a high-k dielectric and metal gate (HKMG)formed over a Si substrate is standard. Next generation FinFETs may beGe FET, SiGe FET, a GAA (gate-all-around) FET. For a demonstrationpurpose, a planar transistor is shown in FIG. 1. The transistor portionis formed on a substrate 100. In some embodiments, the substrate 100includes a single crystalline semiconductor layer on at least itssurface portion. The substrate 100 may include a single crystallinesemiconductor material such as, but not limited to Si, Ge, SiGe, GaAs,InSb, GaP, GaSb, InAlAs, InGaAs, GaSbP, GaAsSb and InP. In certainembodiments, the substrate 100 is made of crystalline silicon.

In FIG. 1, the semiconductor device includes a buffer layer 110. In someembodiments, the buffer layer 110 is a SiGe layer or an oxide layer suchas silicon oxide, titanium oxide, molybdenum oxide, zinc oxide, indiumoxide, tungsten oxide, magnesium oxide, calcium oxide, tin oxide, or thelike. In some embodiments, the buffer layer 110 has a function ofadjusting the stress and strain of a layer formed over it. In someembodiments, the buffer layer 110 prevents leakage current passed from alayer formed over it to other devices formed on the substrate 100.Generally, a SiGe buffer is used for SiGe FET or Ge FET. For Si FET, nobuffer layer is used and the buffer layer 110 is removed from the Si FETin some embodiments.

In FIG. 1, the semiconductor device also includes a first well layer120, a part of which is used for a channel for charge carrier transportin the transistor portion. In some embodiments, the first well layer 120is appropriately doped. The first well layer 120 includes diffusionregions 140 as source/drain regions (hereinafter, for demonstrationpurpose, the left diffusion region 140 is assigned as a source regionand the right diffusion region 140 is assigned as a drain region of thetransistor portion. One of ordinary skill in the art understands thatthe left and right diffusion regions 140 can alternatively be drain andsource regions, respectively, of the transistor). The diffusion regions140 are formed by doping the first well layer 120 by an ion implantationmethod. The transistor portion further includes an isolation insulatinglayer 130 which is also called a shallow trench isolation (STI) layer.The isolation insulating layer 130 is made of suitable dielectricmaterials such as silicon oxide, silicon nitride, silicon oxynitride,fluorine-doped silicate glass (FSG), low-k dielectrics such as carbondoped oxides, extremely low-k dielectrics such as porous carbon dopedsilicon dioxide, a polymer such as polyimide, and combinations thereof.

In some embodiments, the transistor portion further includes secondsemiconductor layers 150 disposed on the source/drain regions 140, as asource/drain structure.

Between the source/drain regions 140, the transistor portion includes agate stack which is formed of a gate dielectric layer 160 on the channelregion of the first well layer 120 between the source/drain regions 140,and a gate electrode layer 170. In some embodiments, the gate electrodelayer 170 is a single layer or multilayer structure. In someembodiments, the gate electrode layer 170 is poly-silicon. Further, thegate electrode layer 170 is doped poly-silicon with uniform ornon-uniform doping, in some embodiments. In some alternativeembodiments, the gate electrode layer 170 includes a metal, such as Al,Cu, W, Ti, Ta, TiN, TiAl, TiAlN, TaN, NiSi, CoSi, other conductivematerials with a work function compatible with the substrate material,or combinations thereof. In the present embodiment, the gate electrodelayer 170 has a thickness in a range of about 20 nm to about 100 nm.

In some embodiments, the gate dielectric layer 160 includes siliconoxide, silicon nitride, silicon oxy-nitride, or high-k dielectrics. Thehigh-k dielectrics include metal oxides. Examples of metal oxides usedfor high-k dielectrics include oxides of Li, Be, Mg, Ca, Sr, Sc, Y, Zr,Hf, Al, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and/ormixtures thereof. In the present embodiment, the gate dielectric layer160 is a high-k dielectric layer with a thickness in the range of about1 nm to about 5 nm. In some embodiments, the gate dielectric layer 160further includes an interfacial layer (not shown) to reduce damagebetween the gate dielectric layer 160 and channel of the first welllayer 120. The interfacial layer includes a chemically formed siliconoxide in some embodiments.

The gate stack is surrounded by sidewall spacers 180 which separate thegate stack from the source/drain regions 140. The sidewall spacers 180include one or more of SiN, SiON, SiCN, SiCO, SiOCN or any othersuitable dielectric material.

The transistor portion is covered by first interlayer dielectric (ILD)layers 300 a, 300 b, 300 d, 300 f, 300 h, 300 j, and 300 l, in whichthrough holes are formed, respectively, and vias 190 a, 190 b, 190 c,190 d, 190 e, 190 f, 190 g, 190 h, 190 i, 190 j, 190 k, and 1901 areformed by filling the through holes with a conductive material. In someembodiments, the first ILD layers 300 a and 300 b are one layer insteadof two layers. The two ILD layers 300 a and 300 b facilitate deviceformation on the ILD layers (e.g. the controlling device 400 a is formedin the first ILD layer 300 a while the via can be formed in the ILDlayer 300 b). In some embodiments, the vias are formed of anelectrically conducting material including one or more of Co, Ni, W, Ti,Ta, Cu, Al, Mo, TiN, TaN, WSi₂, Ni—Si, Co—Si, WN, TiAlN, TaCN, TaC,TaSiN, metal alloys such as Ti—Al alloy, Al—Cu alloy, other suitablematerials, and/or combinations thereof. In some embodiments, theconductive material is deposited using chemical vapor deposition (CVD),atomic layer deposition (ALD), electro-plating, or physical vapordeposition (PVD) followed by an optional reflow process, or othersuitable film formation process.

The materials for the first ILD layers 300 a, 300 b, 300 d, 300 f, 300h, 300 j, and 3001 include inorganic compounds comprising Si, 0, Cand/or H, such as silicon oxide, SiCOH and SiOC, or organic materials,such as polymers.

The transistor portion is also covered by second interlayer dielectric(ILD) layers 300 c, 300 e, 300 g, 300 i, and 300 k, in which trenchesare formed by patterning the second ILD layers 300 c, 300 e, 300 g, 300i, and 300 k, respectively, and metal layers 200 a, 200 b, 200 c, 210 a,210 b, 210 c, 210 d, 210 e, 210 f, 210 g, and 210 h are formed byfilling the trenches with a conductive material. In some embodiments,the metal layers 200 a, 200 b, 200 c, 210 a, 210 b, 210 c, 210 d, 210 e,210 f, 210 g, and 210 h are formed of an electrically conductingmaterial including one or more of Co, Ni, W, Ti, Ta, Cu, Al, Mo, TiN,TaN, WSi₂, Ni—Si, Co—Si, WN, TiAlN, TaCN, TaC, TaSiN, metal alloys suchas Ti—Al alloy, Al—Cu alloy, other suitable materials, and/orcombinations thereof. In some embodiments, the conductive material isdeposited using chemical vapor deposition (CVD), atomic layer deposition(ALD), electro-plating, or physical vapor deposition (PVD) followed byan optional reflow process, or other suitable film formation process. Insome embodiments, the trenches for the metal layers 200 a, 200 b, 200 c,210 a, 210 b, 210 c, 210 d, 210 e, 210 f, 210 g, and 210 h are patternedin the second ILD layers 300 c, 300 e, 300 g, 300 i, and 300 k beforefilling the through holes to form the vias 190 a, 190 b, 190 c, 190 d,190 e, 190 f, 190 g, 190 h, 190 i, 190 j, 190 k, and 1901, so that themetal layers 200 a, 200 b, 200 c, 210 a, 210 b, 210 c, 210 d, 210 e, 210f, 210 g, and 210 h and the vias 190 a, 190 b, 190 c, 190 d, 190 e, 190f, 190 g, 190 h, 190 i, 190 j, 190 k, and 1901 are formed at the sametime.

The materials for the second ILD layers 300 c, 300 e, 300 g, 300 i, and300 k include inorganic compounds comprising Si, 0, C and/or H, such assilicon oxide, SiCOH and SiOC, or organic materials, such as polymers,in some embodiments. In some embodiments, the second ILD layers 300 c,300 e, 300 g, 300 i, and 300 k are formed of the same material as thefirst ILD layers 300 a, 300 b, 300 d, 300 f, 300 h, 300 j, and 300 l. Insome embodiments, the second ILD layers 300 c, 300 e, 300 g, 300 i, and300 k are formed of a material different from the first ILD layers 300a, 300 b, 300 d, 300 f, 300 h, 300 j, and 300 l.

In FIG. 1, a controlled device 220 is formed at a same height level asthe metal layer 210 c. In some embodiments, the controlled device 220 isa semiconductor component such as a light emitting diode, an organiclight emitting diode, a memory, and a processor. In some embodiments,the controlled device 220 is a memory cell, such as a magnetic randomaccess memory (MRAM) cell, a phase change random access memory (PCRAM)cell and/or a resistance change random access memory (RRAM) cell.

In FIG. 1, all the vias 190 a, 190 b, 190 c, 190 d, 190 e, and 190 f onthe source region 140 overlap and align in the z direction with eachother, forming a vertical routing structure together with pad structuresformed by the metal layers 200 a, 200 b, 200 c, 210 a, 210 b, and 210 c.In some embodiments, all the vias 190 a, 190 b, 190 c, 190 d, 190 e, and190 f on the source region 140 completely overlap each other (i.e. thegreatest in-plane area in x-y plane of the vias overlapping each otherwithout having any part in the in-plane area of any one of the vias notoverlapped). In some embodiments, the geometric centers of the vias andpads are located within a hypothetical circle C (FIG. 2(a)) having adiameter less than about 1.0 nm in the x-y plane. In other embodiments,the diameter of the circle C is less than about 0.5 nm. In someembodiments, the sizes or areas of the overlapping vias, e.g. 190 a and190 b, are not the same.

In FIG. 1, the number of vias is six (6), but the number of vias is notlimited to 6. The number of vias in the vertical routing structure canbe two, three, four or five, or more than six, and up to twenty.

In FIG. 1, a controlled device 220 is formed at a same height level asthe metal layer 210 c. In some embodiments, the controlled device 220performs by receiving different voltages applied by the drain region 140of the transistor portion. The different voltages supplied from thedrain region 140 are due to the different voltages applied to the sourceregion 140 by different controlling devices connected to the metallayers 200 a, 200 b, 200 c, 210 a, 210 b, and/or 210 c.

FIG. 2(a) shows a top plan view of the semiconductor device in FIG. 1.The metal layer 200 c and the metal layer 210 c are formed to extend indifferent directions in some embodiments. That is, in the embodimentshown in FIG. 2(a), the metal layer 200 c extends in the −x direction,and the metal layer 210 c extends in the −y direction.

In FIG. 2(a), the metal layer 200 c has one end portion contacting a via190 f which overlaps a source region 140 of the transistor portion. Themetal layer 200 c has an opposite end portion contacting a via 190 nwhich is connected to another metal layer or is electrically connectedto a device 400 a, such as a capacitor, a resistor, a transistor, aprocessor, a logic circuit, a driver circuit and combinations thereof(FIG. 2(a)). The device 400 a includes a controlling device thatcontrols a voltage applied to the source region 140, and in this way,the operation of the controlled device 220 can be controlled by thecontrolling device connected to the via 190 n contacting the metal layer200 c, in some embodiments.

In FIG. 2(a), the metal layer 210 c has one end portion contacting a via190 f which overlaps a source region 140 of the transistor portion. Themetal layer 210 c has an opposite end portion contacting a via 190 mwhich is connected to another metal layer or electrically connected to adevice, such as a capacitor, a transistor, a processor, a logic circuit,a driver circuit and combinations thereof, in some embodiments. Thedevice includes a controlling device that controls a voltage applied tothe source region 140, and in this way, the operation of the controlleddevice 220 of the semiconductor device can be controlled by thecontrolling device connected to the via 190 m contacting the metal layer210 c, in some embodiments. Thus, the controlled device 220 can becontrolled by the controlling devices connected to the vias 190 n and/or190 m. In some embodiments, the controlling devices (not shown in FIG.2(a)) directly contact the metal layers e.g. 190 n and 190 m, and notthrough any vias.

The operation of the controlled device 220 is dependent upon acombination of voltages (signals) applied by the controlling devices(not shown in FIG. 2(a)) to the source region 140 of the transistorportion through the metal layers 190 n and 190 m, in some embodiments.The higher the number of the controlling devices, the higher the numberof combinations of signals applied to the source region 140, the higherthe number of possible ways the operation of the controlled device 220can be performed and the more versatile the controlled device 220.

FIG. 2(b) shows a top plan view of an alternative embodiment of FIG.2(a). In FIG. 2(b), the metal layer 200 c and the metal layer 210 c areformed to extend in different directions in some embodiments. That is,in the embodiment shown in FIG. 2(b), the metal layer 200 c extends inthe −x direction, and the metal layer 210 c extends in the −y directionand then in the −x direction. That is, the metal layer 210 c is a bentmetal layer and not a straight metal layer. The metal layer 210 c isformed to fulfill a specific circuit design of the semiconductor device,for example, for small controlling devices connected to the metal layers190 n and/or 190 m.

In FIG. 2(b), the metal layer 200 c has one end portion contacting a via190 f which overlaps a source region 140 of the transistor portion. Themetal layer 200 c has an opposite end portion contacting a via 190 nwhich is connected to another metal layer or is electrically connectedto a device 400 a, such as a capacitor, a resistor, a transistor, aprocessor, a logic circuit, a driver circuit and combinations thereof.The device 400 a includes a controlling device that controls a voltageapplied to the source region 140, and in this way, the operation of thecontrolled device 220 can be controlled by the controlling deviceconnected to the via 190 n contacting the metal layer 200 c, in someembodiments. In some embodiments, the controlling device 400 a directlycontacts the metal layer 200 c and not through any via.

In FIG. 2(b), the metal layer 210 c has one end portion contacting a via190 f which overlaps a source region 140 of the transistor portion. Themetal layer 210 c has an opposite end portion contacting a via 190 mwhich is connected to another metal layer or electrically connected to adevice 410 a, such as a capacitor, a transistor, a processor, a logiccircuit, a driver circuit and combinations thereof, in some embodiments.The device 410 a includes a controlling device that controls a voltageapplied to the source region 140, and in this way, the operation of thecontrolled device 220 can be controlled by the controlling deviceconnected to the via 190 m contacting the metal layer 210 c, in someembodiments. In some embodiments, the controlling device 410 a directlycontacts the metal layer 210 c and not through any via.

The operation of the controlled device 220 is dependent upon acombination of voltages (signals) applied by the controlling devicese.g. 400 a and 410 a to the source region 140 of the transistor portionthrough the metal layers 190 n and 190 m respectively, in someembodiments. The higher the number of the controlling devices, thehigher the number of combinations of signals applied to the sourceregion 140, the higher the number of possible ways the operation of thecontrolled device 220 can be performed, and the more versatile thecontrolled device 220.

FIG. 2(c) shows a top plan view of an alternative embodiment of FIG.2(a). In FIG. 2(c), metal layer 210 h and metal layer 210 c extend inthe same direction. In some embodiments, the metal layer 210 h and themetal layer 210 c extend in different directions such as perpendiculardirections, i.e., the x and −y directions. The metal layer 210 hcontacts a via 190 o and a controlling device (not shown in FIG. 2(c))connects to the via 190 o to control the controlled device 220 at thedrain side. That is, the voltage generated by the drain region isaltered by the voltage applied by the controlling device through the via190 o and the metal layer 210 h to achieve a desired performance of thecontrolled device 220.

In FIG. 2(c), the metal layer 200 c has one end portion contacting a via190 f which overlaps a source region 140 of the transistor portion. Themetal layer 200 c has an opposite end portion contacting a via 190 nwhich is connected to another metal layer or is electrically connectedto a device 400 a, such as a capacitor, a resistor, a transistor, aprocessor, a logic circuit, a driver circuit and combinations thereof(FIG. 2(c)). The device 400 a includes a controlling device thatcontrols a voltage applied to the source region 140, and in this way,the operation of the controlled device 220 can be controlled by thecontrolling device connected to the via 190 n contacting the metal layer200 c, in some embodiments.

In FIG. 2(c), the metal layer 210 c has one end portion contacting a via190 f which overlaps a source region 140 of the transistor portion. Themetal layer 210 c has an opposite end portion contacting a via 190 mwhich is connected to another metal layer or electrically connected to adevice 410 a, such as a capacitor, a transistor, a processor, a logiccircuit, a driver circuit and combinations thereof, in some embodiments.The device 410 a includes a controlling device that controls a voltageapplied to the source region 140, and in this way, the operation of thecontrolled device 220 can be controlled by the controlling deviceconnected to the via 190 m contacting the metal layer 210 c, in someembodiments. In some embodiments, the controlling device 410 a directlycontacts the metal layer 210 c and not through any via.

The embodiment in FIG. 2(c) further includes a metal layer 210 h. Themetal layer 210 h has one end portion contacting a via 1901 whichoverlaps a drain region 140 of the transistor portion. The metal layer210 h has an opposite end portion contacting a via 190 o which isconnected to another metal layer or electrically connected to a device410 e, such as a capacitor, a transistor, a processor, a logic circuit,a driver circuit and combinations thereof, in some embodiments. Thedevice 410 e includes a controlling device that controls a voltageapplied to the drain region 140, and in this way, the operation of thecontrolled device 220 can be controlled by the controlling deviceconnected to the via 190 o contacting the metal layer 210 h, in someembodiments. In some embodiments, the controlling device 410 e directlycontacts the metal layer 210 h and not through any via.

The operation of the controlled device 220 is dependent upon acombination of voltages (signals) applied by the controlling devicese.g. 400 a, 410 a, and 410 e to the source region 140 of the transistorportion through the metal layers 190 n and 190 m respectively, in someembodiments. The higher the number of the controlling devices, thehigher the number of combinations of signals applied to the sourceregion 140, the higher the number of possible ways the operation of thecontrolled device 220 can be performed and the more versatile thecontrolled device 220.

In some embodiments, the vias 190 f, 190 m, 190 n, 1901, and 190 o havea rectangular in-plane cross-sectional shape. In some embodiments, thevias 190 f, 190 m, 190 n, 1901, and 190 o have an in-planecross-sectional shape of a circle, an oval, a triangle, a square, asquare with rounded corners, a pentagon, a hexagon, or the like. In someembodiments, the overlapping vias such as the vias in the source regionside, have the same in-plane cross-sectional shape while the overlappingvias such as the vias in the drain region side have the same in-planecross-sectional shape. In some embodiments, the vias in the sourceregion side have an in-plane cross-sectional shape different from thevias in the drain region side. In some embodiments, the vias in thesource region side have an in-plane cross-sectional shape the same asthe vias in the drain region side.

FIG. 3, 4, 5, 6, 7, 8(a) or 8(b), 9(a) or 9(b), and 10(a) or 10(b) showsequential manufacturing operations of forming a portion of thesemiconductor device in FIG. 1, according to embodiments of the presentdisclosure. It is understood that in the sequential manufacturingprocess, one or more additional operations can be provided before,during, and after the stages shown in FIGS. 3-10, and some of theoperations described below can be replaced or eliminated for additionalembodiments of the method. The order of the operations/processes may beinterchangeable. In FIG. 3, a buffer layer 110 is formed on a substrate100 by a deposition method, such as chemical vapor deposition (CVD),including low pressure CVD (LPCVD) and plasma enhanced CVD (PECVD),atomic layer deposition (ALD), physical vapor deposition (PVD), such aspulsed laser deposition (PLD), sputtering, evaporative deposition, orother suitable process such as wet thermal oxidation method. In someembodiments, the buffer layer 110 is a SiGe layer.

In FIG. 4, a first well layer 120 is formed over the substrate 100 by adeposition method, such as chemical vapor deposition (CVD), includinglow pressure CVD (LPCVD) and plasma enhanced CVD (PECVD), atomic layerdeposition (ALD), physical vapor deposition (PVD), such as pulsed laserdeposition (PLD), sputtering, evaporative deposition, or other suitableprocess. The first well layer 120 is formed to a thickness to reducestress/strain in some embodiments. For example, but not limited to, thefirst well layer 120 is formed to have a thickness of about 2 nm toabout 20 nm in some embodiments. The first well layer 120 includes agermanium layer or a silicon layer, in some embodiments. Also, the firstwell layer 120 is doped by an n-type dopant to increase the chargecarrier concentrations, and the n-type dopant includes phosphorus, incertain embodiments. The doping operation can be carried out by in-situdoping during deposition of the first well layer 120 and/or ionimplantation. In this way, the first well layer 120 can be a phosphorusdoped germanium layer or a phosphorus doped silicon layer. In someembodiments, the buffer layer 110 is not formed, and the substrate 100is partially doped with appropriate dopant, thereby forming a well layer120.

In FIG. 5, shallow trench isolation (STI) layers, which are also calledisolation insulating layers 130, are formed through an etching process,a film forming process, such as CVD, flowable CVD (FCVD), or aspin-on-glass process, and a planarization process, such as chemicalmechanical polishing, although any acceptable process may be utilized.In other embodiments, the STI layers 130 are formed before the welllayers 120 and/or buffer layer 110 are formed, and the well layers 120and/or the buffer layer 110 are formed over the surface of thesemiconductor substrate 100 where no STI layer is formed.

In FIGS. 6 and 7, a gate stack is formed on the first well layer 120,and the gate stack includes gate dielectric layer 210 and gate electrodelayer 220. The gate dielectric layer 210 is formed using a suitableprocess such as physical vapor deposition (PVD), chemical vapordeposition (CVD), atomic layer deposition (ALD), thermal oxidation,UV-ozone oxidation, or combinations thereof. The gate electrode layer220 can be formed by using CVD, including LPCVD and PECVD, PVD, ALD, orother suitable process. The formed gate electrode layer 220 and the gatedielectric layer 210 are patterned by photolithographic and etchingmethods. In some embodiments, a gate replacement technology is used.

FIG. 8(b) shows an operation to form diffusion regions at source anddrain regions 140 in the first well layer 120. The diffusion regions areformed by doping the first well layer 120 by ion implantation using thegate electrode layer 220 as a mask. The dopant concentration is in arange from about 5×10¹⁷ to about 5×10¹⁸ cm⁻³ in some embodiments.

FIG. 9(b) shows an operation of forming the sidewall spacer 180surrounding the gate stack. The sidewall spacer 180 can be formed by ALDor CVD, or any other suitable method and anisotropic etching.

In FIG. 10(b), in some embodiments, the second semiconductor layer 150is epitaxially grown on the source and drain regions 140 in the firstwell layer 120 by a method including LPCVD and PECVD, PVD, ALD, or othersuitable process, such as epitaxy methods including vapor-phase epitaxy(VPE), chemical vapor deposition, molecular-beam epitaxy (MBE),liquid-phase epitaxy (LPE). The second semiconductor layer 150 is formedto a thickness to apply stress/strain in the structure. For example, butnot limited to, the second semiconductor layer 150 is formed to have athickness of about 2 nm to about 20 nm in some embodiments. The secondsemiconductor layer 150 includes a SiGe, SiP, SiC, and/or SiCP layer, insome embodiments. Also, the second semiconductor layer 150 is doped byan n-type dopant to increase the charge carrier concentrations, and then-type dopant includes phosphorus, in certain embodiments. The dopingoperation can be carried out by in-situ deposition or ion implantation.In this way, the second semiconductor layer 150 can be a phosphorusdoped silicon layer. The P doped Si layer can reduce contact resistanceat the interface between a metal layer such as via 190 a (FIG. 1) andthe second semiconductor layer 150.

In some embodiments, instead of forming the source and drain regions 140by ion implantation (FIG. 8(b)) and forming the second semiconductorlayer 150 thereon (FIG. 10(b)), as shown in FIGS. 8(b), 9(b), and 10(b),regions of the first well layer 120 (FIG. 8(a)) to be source and drainregions are recessed by one or more lithography and etching operations,forming the recesses 140′ in FIG. 9(a), and the second semiconductorlayer 150 is epitaxially formed in and over the recesses 140′ in FIG.10(a). In some embodiments, the recesses 140′ are formed after thesidewall spacer 180 is formed (FIG. 9(a)). In some embodiment, thesecond semiconductor layer 150 is selectively formed in and over therecess 140′.

FIG. 11 shows an operation of forming a dielectric structure on thetransistor portion and the substrate 100. The operation of forming thedielectric structure is performed using a deposition technique, such asa chemical vapor deposition (CVD) technique or a physical vapordeposition (PVD) technique. In some embodiments, the operation offorming the dielectric structure includes forming ILD layers 300 a and300 b stacked on each other. In some embodiments, the ILD layers 300 aand 300 b are formed from silicon oxide, SiOC, SiON and/or SiOCN. Insome embodiments, the ILD layers 300 a and 300 b are formed of the samematerial deposited continuously. In some embodiments, the ILD layers 300a and 300 b are formed of different materials. Depending on thematerials used to form the ILD layers 300 a and 300 b, etching rates ofthe ILD layers 300 a and 300 b are the same for the ILD layers 300 a and300 b formed of the same material, and etching rates of the ILD layers300 a and 300 b are different for the ILD layers 300 a and 300 b formedof the different materials. For different etching rates, the ILD layer300 a can act as an etch stop layer while the ILD layer 300 b is etchedto form structures such as through holes on the ILD layer 300 a forvias. In this situation, the ILD layer 300 a completely covers thetransistor portion (not shown). 150

FIG. 12 shows an operation of forming through holes in the ILD layer 300b. In some embodiments, the operation of forming the through holesincludes removing a portion of the ILD layer 300 b using an etchingtechnique, such as a dry etching technique, a photolithographic andetching method, directional etching method, and cyclotron resonanceplasma etching. Vias 190 a and 190 g are formed by filling the throughholes using a method such as chemical vapor deposition (CVD), includinglow pressure CVD (LPCVD) and plasma enhanced CVD (PECVD), atomic layerdeposition (ALD), non-conformal physical vapor deposition (PVD) such aspulsed laser deposition (PLD), sputtering, evaporative deposition,cathodic arc deposition, e-beam physical vapor deposition, or othersuitable process. In some embodiments, the vias 190 a and 190 g arethrough vias that completely penetrate the ILD layer 300 b. In someembodiments, each of the vias 190 a and 190 g has a vertical portionpenetrating the ILD layer 300 b and another vertical portion notpenetrating the ILD layer 300 b, and in this way, the via 190 a or 190 gpartially penetrates the ILD layer 300 b. This structure of the via 190a or 190 g functions to adjust the resistance along the vertical axis ofthe via 190 a or 190 g so as to fulfill a specific device design forcarrying out specific functions of the device for various purposes. Insome embodiments, this partially penetrating via structure functions tobalance the resistances of the vias 190 a and 190 g to achieve the sameresistance value of the device. In some embodiments, this partiallypenetrating via structure has different resistances at the sourceportion 140 and the drain portion 140 to achieve a specific transistorportion for specific purposes.

FIG. 13 shows an operation of forming the ILD layer 300 c and metallayers 200 a and 210 d in the ILD layer 300 c. In some embodiments, theoperation of forming the ILD layer 300 c is performed using a depositiontechnique, such as a chemical vapor deposition (CVD) technique or aphysical vapor deposition (PVD) technique. In some embodiments, the ILDlayer 300 c is formed from silicon nitride, silicon carbide or siliconoxide. In some embodiments, the ILD layer 300 c is formed of the samematerial as the ILD layer 300 b. In some embodiments, the ILD layer 300c is formed of a material different from the ILD layer 300 b. Dependingon the materials used to form the ILD layers 300 c and 300 b, etchingrates of the ILD layers 300 c and 300 b are the same for the ILD layers300 c and 300 b formed of the same material, and etching rates of theILD layers 300 c and 300 b are different for the ILD layers 300 c and300 b formed of the different materials.

The formed ILD layer 300 c is patterned to form trenches to be filled bya metal to form metal layers 200 a and 210 d. In some embodiments, thepatterning technique is a photolithographic and etching method such asDUV photolithography using a mask and plasma etching, or a cyclotronplasma etching method. Metal layers 200 a and 210 d are formed byfilling the trenches using a method such as chemical vapor deposition(CVD), including low pressure CVD (LPCVD) and plasma enhanced CVD(PECVD), atomic layer deposition (ALD), non-conformal physical vapordeposition (PVD) such as pulsed laser deposition (PLD), sputtering,evaporative deposition, cathodic arc deposition, e-beam physical vapordeposition, or other suitable process. In some embodiments, the metallayers 200 a and 210 d are formed of a material from among the abovedescribed materials used to form the vias 190 a and 190 g. In someembodiments, the metal layers 200 a and 210 d are formed of the samematerial as the vias 190 a and 190 g. In some embodiments, the metallayers 200 a and 210 d are formed of a material different from the vias190 a and 190 g. In some embodiments, the metal layers 200 a and 210 dand the vias are formed in the same process in the same processingchamber. In some embodiments, the metal layers 200 a and 210 d and thevias 190 a and 190 g are formed in separate processes which are carriedout in the same chamber or in different chambers through a wafertranslation mechanism. In some embodiments, a dual damascene method isapplied.

In FIGS. 14, 15, and 16, the formation of the ILD layers 300 d, 300 e,300 f, 300 g, 300 h, 300 i, 300 j, 300 k, and 300 l, the formation ofvias 190 b, 190 c, 190 d, 190 e, 190 f, 190 h, 190 i, 190 j, 190 k,1901, and the formation of metal layers 200 b, 200 c, 210 a, 210 b, 210c, 210 e, 210 f, 210 g, and 210 h use the above described operations inFIGS. 11, 12, and 13. In some embodiments, the operations in FIGS. 14,15, and 16 are carried out in any combination of methods and materials,including same method, different methods, same method for some layersand different methods for some layers, same material and differentmaterials.

In FIG. 17, a controlled device 220 is formed at a same height level asthe metal layer 210 c. In some embodiments, the controlled device 220 isa semiconductor component such as a light emitting diode, an organiclight emitting diode, a memory, and a processor. In some embodiments,the controlled device 220 performs by receiving different voltagesapplied by the drain region 140 of the transistor portion.

FIG. 18 shows a cross-sectional view of a semiconductor device,according to another embodiment of the present disclosure. In FIG. 18,controlling devices 400 a, 400 b and 400 c are formed and connected tothe metal layers 200 a, 200 b and 200 c, respectively, to apply variedcontrol to voltages applied to the source region. In some embodiments,each of the controlling devices 400 a, 400 b and 400 c applies a samevoltage to the source region 140. In some embodiments, each of thecontrolling devices 400 a, 400 b and 400 c applies a different or thesame voltage to the source region. Although hidden in the view of FIG.18, controlling devices 410 a, 410 b, and 410 c (outlined by brokenlines) connect with metal layers 210 a, 210 b, and 210 c, respectively,to apply varied control to voltages applied to the source region. Thecombined voltage of the voltages applied controls the source region 140and the transistor portion. In the embodiment in FIG. 18, the drainregion 140 does not have any controlling device connected to the metallayers 210 d, 210 e, 210 f, 210 g, and 210 h. In this way, thecontrollability of the controlled device 220 can be further enhancedthrough the vertical structure while reducing the surface area of thesubstrate 100.

FIG. 19 shows a cross-sectional view of a semiconductor device,according to another embodiment of the present disclosure. Thesemiconductor device in FIG. 19 is similar to the embodiment in FIG. 18,except the end portions of the metal layers 210 d, 210 e, 210 f, 210 g,and 210 h opposite to the stacked vias are connected to controllingdevices 410 d, 410 e, 410 f, 410 g, and 410 h, respectively, so as toreceive the same or different voltages from the controlling devices 410d, 410 e, 410 f, 410 g, and 410 h. In this way, the controllability ofthe controlled device 220 can be further enhanced through the verticalstructure while reducing the surface area of the substrate 100. Thecontrolling devices indicated by broken lines are located the endportions of the metal layers away from the vias, and the broken linesare used to indicate the overlapping positions of the controllingdevices along y axis.

FIG. 20 shows a flow chart of a method of forming the semiconductordevice in FIG. 1, according to embodiments of the present disclosure.The method includes operations S2001: providing a substrate, S2002:forming a thin film transistor having a source region and a drain regionon the substrate. After operation S2002, two sets of operationsS2003-S2007 and S2008-S2012 are performed on the source region and thedrain region, either simultaneously on both the source and drainregions, or separately in a sequence of finishing the sequence on thesource region and then finishing the sequence on the drain region. Thatis, the method includes, at S2003 (i.e. on the source region),operations of S2004: forming a first via on the source region, S2005:forming a first metal layer extending along a first direction on thefirst via, S2006: forming a second via completely overlapping the firstvia on the first metal layer, and S2007: forming a second metal layerextending along a second direction different from the first direction onthe second via. The method also includes, at S2008 (i.e. on the drainregion), operations of S2009: forming a third via at the same heightlevel as the first via on the drain region, S2010: forming a third metallayer on the third via, S2011: forming a fourth via completelyoverlapping the third via on the third metal layer, and S2012: forming acontrolled device on the fourth via, and the device is at the sameheight level as the second metal layer and controlled by the thin filmtransistor.

FIG. 21 shows a semiconductor device having a vertical routingstructure, according to an embodiment of the present disclosure. In someembodiments, the semiconductor device includes a transistor portion. Insome embodiments, the transistor portion includes a planar transistor.In some embodiments, the transistor portion includes a surrounding gatetransistor or a FinFET. For a demonstration purpose, a planar transistor(FET) is shown in FIG. 21 as an example. The transistor portion isformed on a substrate 100. In some embodiments, the substrate 100includes a single crystalline semiconductor layer on at least itssurface portion. In some embodiments, the substrate 100 includes asingle crystalline semiconductor material such as, but not limited toSi, Ge, SiGe, GaAs, InSb, GaP, GaSb, InAlAs, InGaAs, GaSbP, GaAsSb andInP. In certain embodiments, the substrate 100 is made of crystallinesilicon.

In FIG. 21, the semiconductor device includes a buffer layer 110. Insome embodiments, the buffer layer 110 is a SiGe layer or an oxide layersuch as silicon oxide, titanium oxide, molybdenum oxide, zinc oxide,indium oxide, tungsten oxide, magnesium oxide, calcium oxide, tin oxide,or the like. In some embodiments, the buffer layer 110 has a function ofadjusting the stress and strain of a layer formed over it. In someembodiments, the buffer layer 110 prevents leakage current passed from alayer formed over it to other devices formed on the substrate 100.

In FIG. 21, the semiconductor device also includes a first well layer120, a part of which is used for a channel for charge carrier transportin the transistor portion. In some embodiments, the first well layer 120is formed of a semiconducting material such as crystalline silicon andgermanium. The first well layer 120 is disposed on the buffer layer 110on the substrate 100. The first well layer 120 includes diffusionregions 140 as source and drain regions (hereinafter, for demonstrationpurpose, the left diffusion region 140 is assigned as source region andthe right diffusion region 140 is assigned as drain region of thetransistor portion; and one of ordinary skill in the art wouldunderstand that the left and right diffusion regions 140 can be drainand source regions, respectively, of the transistor). The diffusionregions 140 are formed by doping the first well layer 120 by using anion implantation method. The transistor portion further includes anisolation insulating layer 130 which is also called a shallow trenchisolation (STI) layer. The isolation insulating layer 130 is made ofsuitable dielectric materials such as silicon oxide, silicon nitride,silicon oxynitride, fluorine-doped silicate glass (FSG), low-kdielectrics such as carbon doped oxides, extremely low-k dielectricssuch as porous carbon doped silicon dioxide, a polymer such aspolyimide, and combinations of these.

The transistor portion further includes second semiconductor layers 150disposed on the source and drain regions 140.

Between the source and drain regions 140, the transistor portionincludes a gate stack which is formed of a gate dielectric layer 160 onchannel region of the first well layer 120 between the source and drainregions 140, and a gate electrode layer 170. In some embodiments, thegate electrode layer 170 is a single layer or multilayer structure. Insome embodiments, the gate electrode layer 170 is poly-silicon. Further,the gate electrode layer 170 is doped poly-silicon with uniform ornon-uniform doping, in some embodiments. In some alternativeembodiments, the gate electrode layer 170 includes a metal, such as Al,Cu, W, Ti, Ta, TiN, TiAl, TiAlN, TaN, NiSi, CoSi, other conductivematerials with a work function compatible with the substrate material,or combinations of these. In the present embodiment, the gate electrodelayer 170 has a thickness in a range of about 20 nm to about 100 nm.

In some embodiments, the gate dielectric layer 160 includes siliconoxide, silicon nitride, silicon oxy-nitride, or high-k dielectrics. Thehigh-k dielectrics include metal oxides. Examples of metal oxides usedfor high-k dielectrics include oxides of Li, Be, Mg, Ca, Sr, Sc, Y, Zr,Hf, Al, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and/ormixtures thereof. In the present embodiment, the gate dielectric layer160 is a high-k dielectric layer with a thickness in the range of about1 to about 5 nm. In some embodiments, the gate dielectric layer 160further includes an interfacial layer (not shown) to reduce damagebetween the gate dielectric layer 160 and channel of the first welllayer 120. The interfacial layer includes chemically formed siliconoxide in some embodiments.

The gate stack is surrounded by sidewall spacers 180 which separate thegate stack from the source and drain regions 140. The sidewall spacers180 include one or more of SiN, SiON, SiCN, SiCO, SiOCN or any othersuitable dielectric material.

The transistor portion is covered by first interlayer dielectric (ILD)layers 300 a, 300 b, 300 d, 300 f, 300 h, 300 j, and 300 l in whichthrough holes are formed respectively, and vias 190 a, 190 b, 190 c, 190d, 190 e, 190 f, 190 g, 190 h, 190 i, 190 j, 190 k, and 1901 surroundedby protective layers 190 a′, 190 b′, 190 c′, 190 d′, 190 e′, 190 f′, 190g′, 190 h′, 190 i′, 190 j′, 190 k′, and 1901′ respectively formed byfilling the protective layer coated through holes with a conductivematerial. In some embodiments, the protective layers 190 a′, 190 b′, 190c′, 190 d′, 190 e′, 190 f′, 190 g′, 190 h′, 190 i′, 190 j′, 190 k′, and1901′ are formed of a material such as titanium nitride or tantalumnitride. The protective layers function as a barrier layer to preventdiffusion of a material into the vias surrounded by the protectivelayers that contaminate the vias and affect the pre-designed resistancesof the vias, and prevent diffusion of conducting material to the ILDlayers that create leakage current pathways. In some embodiments, theprotective layers 190 a′, 190 b′, 190 c′, 190 d′, 190 e′, 190 f′, 190g′, 190 h′, 190 i′, 190 j′, 190 k′, and 1901′ are formed by anelectro-plating method such as CVD, MOCVD, and conformal physical vapordeposition method. In some embodiments, the vias are formed of anelectrically conducting material including one or more of Co, Ni, W, Ti,Ta, Cu, Al, Mo, TiN, TaN, WSi₂, Ni—Si, Co—Si, WN, TiAlN, TaCN, TaC,TaSiN, metal alloys such as Ti—Al alloy, Al—Cu alloy, other suitablematerials, and/or combinations thereof. In some embodiments, theconductive material is deposited using chemical vapor deposition (CVD),atomic layer deposition (ALD), electro-plating, or physical vapordeposition (PVD) followed by an optional reflow process, or othersuitable film formation process.

The materials for the first ILD layers 300 a, 300 b, 300 d, 300 f, 300h, 300 j, and 3001 include inorganic compounds comprising Si, 0, Cand/or H, such as silicon oxide, SiCOH and SiOC, or organic materials,such as polymers.

The transistor portion is also covered by second interlayer dielectric(ILD) layers 300 c, 300 e, 300 g, 300 i, and 300 k in which trenches areformed by patterning the second ILD layers 300 c, 300 e, 300 g, 300 i,and 300 k, respectively. Metal layers 200 a, 200 b, 200 c, 210 a, 210 b,210 c, 210 d, 210 e, 210 f, 210 g, and 210 h are formed by filling thetrenches with a conductive material. In some embodiments, the metallayers 200 a, 200 b, 200 c, 210 a, 210 b, 210 c, 210 d, 210 e, 210 f,210 g, and 210 h are formed of an electrically conducting materialincluding one or more of Co, Ni, W, Ti, Ta, Cu, Al, Mo, TiN, TaN, WSi₂,Ni—Si, Co—Si, WN, TiAlN, TaCN, TaC, TaSiN, metal alloys such as Ti—Alalloy, Al—Cu alloy, other suitable materials, and/or combinationsthereof. In some embodiments, the conductive material is deposited usingchemical vapor deposition (CVD), atomic layer deposition (ALD),electro-plating, or physical vapor deposition (PVD) followed by anoptional reflow process, or other suitable film formation process. Insome embodiments, the trenches for the metal layers 200 a, 200 b, 200 c,210 a, 210 b, 210 c, 210 d, 210 e, 210 f, 210 g, and 210 h are patternedin the second ILD layers 300 c, 300 e, 300 g, 300 i, and 300 k beforefilling the through holes to form the vias 190 a, 190 b, 190 c, 190 d,190 e, 190 f, 190 g, 190 h, 190 i, 190 j, 190 k, and 1901, so that themetal layers 200 a, 200 b, 200 c, 210 a, 210 b, 210 c, 210 d, 210 e, 210f, 210 g, and 210 h and the vias 190 a, 190 b, 190 c, 190 d, 190 e, 190f, 190 g, 190 h, 190 i, 190 j, 190 k, and 1901 are formed at the sametime.

The materials for the second ILD layers 300 c, 300 e, 300 g, 300 i, and300 k include inorganic compounds comprising Si, O, C and/or H, such assilicon oxide, SiCOH and SiOC, or organic materials, such as polymers,in some embodiments. In some embodiments, the second ILD layers 300 c,300 e, 300 g, 300 i, and 300 k are formed of the same material as thefirst ILD layers 300 a, 300 b, 300 d, 300 f, 300 h, 300 j, and 300 l. Insome embodiments, the second ILD layers 300 c, 300 e, 300 g, 300 i, and300 k are formed of a material different from the first ILD layers 300a, 300 b, 300 d, 300 f, 300 h, 300 j, and 300 l.

In FIG. 21, a controlled device 220 is formed at the same height levelas the metal layer 210 c. In some embodiments, the controlled device 220is a semiconductor component such as a light emitting diode, an organiclight emitting diode, a memory, and a processor. In some embodiments,the controlled device 220 is a memory cell, such as a magnetic randomaccess memory (MRAM) cell, a phase change random access memory (PCRAM)cell and/or a resistance change random access memory (RRAM) cell.

In FIG. 21, all the vias 190 a, 190 b, 190 c, 190 d, 190 e, and 190 f onthe source region 140 overlap each other, forming a vertical routingstructure with trenches occupied by the metal layers 200 a, 200 b, 200c, 210 a, 210 b, and 210 c. In some embodiments, all the vias 190 a, 190b, 190 c, 190 d, 190 e, and 190 f on the source region 140 completelyoverlap each other (i.e. the greatest in-plane area in x-y plane of thevias overlapping each other without having any part in the in-plane areaof any one of the vias not overlapped).

FIGS. 22, 23, 24, 25, 26, 27, 28, and 29 show sequential manufacturingoperations of forming a portion of the semiconductor device in FIG. 21,according to embodiments of the present disclosure. In FIG. 22, a bufferlayer 110 is formed on a substrate 100 by a deposition method, such aschemical vapor deposition (CVD), including low pressure CVD (LPCVD) andplasma enhanced CVD (PECVD), atomic layer deposition (ALD), physicalvapor deposition (PVD), such as pulsed laser deposition (PLD),sputtering, evaporative deposition, or other suitable process such aswet thermal oxidation method. In some embodiments, the buffer layer 110is a SiGe layer.

In FIG. 23, a first well layer 120 is formed over the substrate 100 by adeposition method, such as chemical vapor deposition (CVD), includinglow pressure CVD (LPCVD) and plasma enhanced CVD (PECVD), atomic layerdeposition (ALD), physical vapor deposition (PVD), such as pulsed laserdeposition (PLD), sputtering, evaporative deposition, or other suitableprocess. The first well layer 120 is formed to a thickness to reducestress/strain in some embodiments. For example, but not limited to, thefirst well layer 120 is formed to have a thickness of about 2 nm toabout 20 nm in some embodiments. The first well layer 120 includes agermanium layer or a silicon layer, in some embodiments. Also, the firstwell layer 120 is doped by an n-type dopant to increase the chargecarrier concentrations, and the n-type dopant includes phosphorus, incertain embodiments. The doping operation can be carried out by in-situdoping during deposition of the first well layer 120 and/or ionimplantation. In this way, the first well layer 120 can be a phosphorusdoped germanium layer or a phosphorus doped silicon layer. In someembodiments, the buffer layer 110 is not formed, and the substrate 100is partially doped with appropriate dopant, thereby forming a well layer120.

In FIG. 24, shallow trench isolation (STI) layers, which are also calledisolation insulating layers 130, are formed through an etching process,a film forming process, such as CVD, flowable CVD (FCVD), or aspin-on-glass process, and a planarization process, such as chemicalmechanical polishing, although any acceptable process may be utilized.

In FIGS. 25 and 26, a gate stack is formed on the first well layer 120,and the gate stack includes gate dielectric layer 210 and gate electrodelayer 220. The gate dielectric layer 210 is formed using a suitableprocess such as physical vapor deposition (PVD), chemical vapordeposition (CVD), atomic layer deposition (ALD), thermal oxidation,UV-ozone oxidation, or combinations thereof. The gate electrode layer220 can be formed by using CVD, including LPCVD and PECVD, PVD, ALD, orother suitable process. The formed gate electrode layer 220 and the gatedielectric layer 210 are patterned by photolithographic and etchingmethods. In some embodiments, a gate replacement technology is used.

FIG. 27 shows an operation to form diffusion regions at source and drainregions 140 in the first well layer 120. The diffusion regions areformed by doping the first well layer 120 by ion implantation, and usingthe gate electrode layer 220 as a mask. The dopant concentration is in arange from about 5×10¹⁷ to about 5×10¹⁸ cm⁻³ in some embodiments.

FIG. 28 shows an operation of forming the sidewall spacer 180surrounding the gate stack. The sidewall spacer 180 can be formed by ALDor CVD, or any other suitable method and anisotropic etching.

In FIG. 29, in some embodiments, the second semiconductor layer 150 isformed on the source and drain regions 140 in the first well layer 120by a deposition method such as chemical vapor deposition (CVD),including low pressure CVD (LPCVD) and plasma enhanced CVD (PECVD),atomic layer deposition (ALD), physical vapor deposition (PVD), such aspulsed laser deposition (PLD), sputtering, evaporative deposition, orother suitable process. The second semiconductor layer 150 is formed toa thickness to apply stress/strain in the structure. For example, butnot limited to, the second semiconductor layer 150 is formed to have athickness of about 2 nm to about 20 nm in some embodiments. The secondsemiconductor layer 150 includes a SiGe, SiP, SiC, and/or SiCP layer, insome embodiments. Also, the second semiconductor layer 150 is doped byan n-type dopant to increase the charge carrier concentrations, and then-type dopant includes phosphorus, in certain embodiments. The dopingoperation can be carried out by in-situ deposition or ion implantation.In this way, the second semiconductor layer 150 can be a phosphorusdoped silicon layer. The P doped Si layer can reduce contact resistanceat the interface between a metal layer such as via 190 a (FIG. 21) andthe second semiconductor layer 150.

FIG. 30 shows an operation of forming a dielectric structure on thetransistor portion and the substrate 100. The operation of forming thedielectric structure is performed using a deposition technique, such asa chemical vapor deposition (CVD) technique or a physical vapordeposition (PVD) technique. In some examples, the operation of formingthe dielectric structure includes forming ILD layers 300 a and 300 bstacked on each other. In some embodiments, the ILD layers 300 a and 300b are formed from silicon nitride, silicon carbide or silicon oxide. Insome embodiments, the ILD layers 300 a and 300 b are formed of the samematerial. In some embodiments, the ILD layers 300 a and 300 b are formedof different materials. Depending on the materials used to form the ILDlayers 300 a and 300 b, etching rates of the ILD layers 300 a and 300 bare the same for the ILD layers 300 a and 300 b formed of the samematerial, and etching rates of the ILD layers 300 a and 300 b aredifferent for the ILD layers 300 a and 300 b formed of the differentmaterials.

FIGS. 31, 32, and 33 show operations of forming through holes,protective layers 190 a′ and 190 g′, and vias 190 a and 190 g in the ILDlayer 300 b. In FIG. 31, in some embodiments, the operation of formingthe through holes include removing a portion of the ILD layer film 300 busing an etching technique, such as a dry etching technique, aphotolithographic and etching method, directional etching method, andcyclotron resonance plasma etching.

In FIG. 32, the protective layers 190 a′, 190 b′, 190 c′, 190 d′, 190e′, 190 f′, 190 g′, 190 h′, 190 i′, 190 j′, 190 k′, and 1901′ are formedon inside surfaces of the through holes by an electro-plating methodsuch as CVD, MOCVD, and conformal physical vapor deposition method. Theprotective layers 190 a′, 190 b′, 190 c′, 190 d′, 190 e′, 190 f′, 190g′, 190 h′, 190 i′, 190 j′, 190 k′, and 1901′ are formed of a materialsuch as titanium nitride or tantalum nitride.

In FIG. 33, vias 190 a and 190 g are formed by filling the through holesusing a method such as chemical vapor deposition (CVD), including lowpressure CVD (LPCVD) and plasma enhanced CVD (PECVD), atomic layerdeposition (ALD), non-conformal physical vapor deposition (PVD) such aspulsed laser deposition (PLD), sputtering, evaporative deposition,cathodic arc deposition, e-beam physical vapor deposition, or othersuitable process. In some embodiments, the vias 190 a and 190 g arethrough vias that completely penetrate the ILD layer 300 b. In someembodiments, each of the vias 190 a and 190 g has a vertical portionpenetrating the ILD layer 300 b and another vertical portion notpenetrating the ILD layer 300 b, and in this way, the via 190 a or 190 gpartially penetrates the ILD layer 300 b. This structure of the via 190a or 190 g functions to adjust the resistance along the vertical axis ofthe via 190 a or 190 g so as to fulfill a specific device design forcarrying out specific functions of the device for various purposes. Insome embodiments, this partially penetrating via structure functions tobalance the resistances of the vias 190 a and 190 g to achieve the sameresistance value of the device. In some embodiments, this partiallypenetrating via structure has different resistances at the sourceportion 140 and the drain portion 140 to achieve a specific transistorportion for specific purposes.

FIG. 34 shows an operation of forming the ILD layer 300 c and metallayers 200 a and 210 d in the ILD layer 300 c. The operation of formingthe ILD film 300 c is performed using a deposition technique, such as achemical vapor deposition (CVD) technique or a physical vapor deposition(PVD) technique. In some embodiments, the ILD layer 300 c is formed fromsilicon nitride, silicon carbide or silicon oxide. In some embodiments,the ILD layer 300 c is formed of the same material as the ILD layer 300b. In some embodiments, the ILD layer 300 c is formed of a materialdifferent from the ILD layer 300 b. Depending on the materials used toform the ILD layers 300 c and 300 b, etching rates of the ILD layers 300c and 300 b are the same for ILD layers 300 c and 300 b formed of thesame material, and etching rates of the ILD layers 300 c and 300 b aredifferent for the ILD layers 300 c and 300 b formed of the differentmaterials.

The formed ILD layer 300 c is patterned to form trenches to be filled bya metal to form metal layers 200 a and 210 d. In some embodiments, thepatterning technique is a photolithographic and etching method such asDUV photolithography using a mask and plasma etching, or a cyclotronplasma etching method. The operation of forming the trenches includesremoving a portion of the ILD layer 300 c using an etching technique,such as a dry etching technique, photolithographic and etching methods,directional etching method, and cyclotron resonance plasma etching.Metal layers 200 a and 210 d are formed by filling the trenches using amethod such as chemical vapor deposition (CVD), including low pressureCVD (LPCVD) and plasma enhanced CVD (PECVD), atomic layer deposition(ALD), non-conformal physical vapor deposition (PVD) such as pulsedlaser deposition (PLD), sputtering, evaporative deposition, cathodic arcdeposition, e-beam physical vapor deposition, or other suitable process.In some embodiments, the metal layers 200 a and 210 d are formed of amaterial from among the above described materials used to form the vias190 a and 190 g. In some embodiments, the metal layers 200 a and 210 dare formed of the same material as the vias 190 a and 190 g. In someembodiments, the metal layers 200 a and 210 d are formed of a materialdifferent from the vias 190 a and 190 g. In some embodiments, the metallayers 200 a and 210 d and the vias are formed in the same process inthe same processing chamber. In some embodiments, the metal layers 200 aand 210 d and the vias 190 a and 190 g are formed in separate processeswhich are carried out in the same chamber or in different chambersthrough wafer translation mechanism. In some embodiments, a dualdamascene method is applied.

In FIG. 35, the formation of additional ILD layers 300 d, 300 e, 300 f,300 g, 300 h, 300 i, 300 j, 300 k, and 300 l, the formation ofadditional vias 190 b, 190 c, 190 d, 190 e, 190 f, 190 h, 190 i, 190 j,190 k, 1901, and the formation of additional metal layers 200 b, 200 c,210 a, 210 b, 210 c, 210 e, 210 f, 210 g, and 210 h use the abovedescribed operations in FIGS. 30, 31, 32, 33, and 34. In someembodiments, the operations in FIGS. 30, 31, 32, 33, 34, and 35 arecarried out in any combination of methods and materials, including samemethod, different methods, same method for some layers and differentmethods for some layers, same material and different materials.

In FIG. 35, a controlled device 220 is formed at the same height levelas the metal layer 210 c. In some embodiments, the controlled device 220is a semiconductor component such as a light emitting diode, an organiclight emitting diode, a memory, and a processor. In some embodiments,the controlled device 220 performs by receiving different voltagesapplied by the drain region 140 of the transistor portion.

FIG. 36 shows a flow chart of a method of forming the semiconductordevice in FIG. 21, according to embodiments of the present disclosure.The method includes operations S3601: providing a substrate, S3602:forming a thin film transistor having a source region and a drain regionon the substrate. After operation S3602, two sets of operationsS3603-S3607 and S3608-S3612 are performed on the source region and thedrain region, either simultaneously on both the source and drainregions, or separately in a sequence of finishing the sequence on thesource region and then finishing the sequence on the drain region. Thatis, the method includes, on the source region (S3603), operations ofS3604: forming a first protective coating and a first via on the sourceregion, S3605: forming a first metal layer extending along a firstdirection on the first via, S3606: forming a second protective coatingand a second via completely overlapping the first via on the first metallayer, and S3607: forming a second metal layer extending along a seconddirection different from the first direction on the second via. Themethod also includes, on the drain region (S3608), operations of S3609:forming a third protective coating and a third via at the same heightlevel as the first via on the drain region, S3610: forming a third metallayer on the third via, S3611: forming a fourth protective coating and afourth via completely overlapping the third via on the third metallayer, and S3612: forming a controlled device on the fourth via, and thedevice is at the same height level as the second metal layer andcontrolled by the thin film transistor.

Along with the evolution of semiconductor integrated circuit (IC)technology, rapid growth of the market and boosted functional densityhave pushed the IC technology from two-dimensional (2D) thin filmtechnology to three-dimensional (3D) device structure. The 2D aspect ofthe 3D device structure still poses a problem of occupying substratearea while more and more functional components are packed for highlycomplicated controls of device components within the IC. For example,controlling multiple voltage levels of a source of a transistor so as toachieve a sophisticated control of a drain of the device, the multiplecontrolling devices would occupy a large surface area of the substrate.The present disclosure provides a device structure that solves the aboveproblem of 3D device structure and pushes the IC technology to a newlevel. In particular, the present disclosure provides a semiconductordevice having a vertical routing structure and method of producing thedevice. The semiconductor device enhances the controllability whileefficiently reducing the substrate surface area occupied by the deviceand controlling devices controlling the device. Also, the deviceenhances complexity of control of the device, pushing the IC technologyand functionality to a new high density level and high versatilitylevel.

The present application discloses an exemplary method of manufacturing asemiconductor device. The method includes forming a transistor having asource region and a drain region on a substrate. On the source region, afirst via is formed over the source region. A first metal layer isformed extending along a first direction on the first via. A second viais formed overlapping the first via over the first metal layer. A secondmetal layer is formed extending along a second direction different fromthe first direction on the second via. On the drain region, a third viais formed at the same height level as the first via and over the drainregion. A third metal layer is formed on the third via. A fourth via isformed over the third metal layer. The fourth via overlaps the thirdvia. A controlled device is formed on the fourth via, and the controlleddevice is at the same height level as the second metal layer andcontrolled by the transistor. In one or more of the foregoing orfollowing embodiments, the first via and the second via have the samearea in a plan view. In one or more of the foregoing or followingembodiments, the first metal layer connects to a controlling devicewhich controls an applied voltage to the first metal layer. In one ormore of the foregoing or following embodiments, the second metal layerconnects to a controlling device which controls an applied voltage tothe second metal layer. In one or more of the foregoing or followingembodiments, the controlled device includes one of an organic lightemitting diode device, a memory and a transistor. In one or more of theforegoing or following embodiments, between the first metal layer andthe second via, the method includes alternately forming a plurality ofvias and metal layers, and all the plurality of vias have the same shape(or area) and all the plurality of metal layers have the same shape (orarea), in plan view.

The present application also discloses an exemplary method ofmanufacturing a semiconductor device. The method includes forming atransistor having a source region and a drain region over a substrate.On the source region, a first via is formed surrounded by a firstprotective layer in a first interlayer dielectric (ILD) layer on thesource region. A first metal layer is formed extending along a firstdirection on the first via. A second via is formed overlapping the firstvia and surrounded by a second protective layer in a second ILD layerover the first metal layer. A second metal layer is formed extendingalong a second direction different from the first direction on thesecond via. On the drain region, a third via is formed at the sameheight level as the first via and surrounded by a third protective layerin the first ILD layer over the drain region. A third metal layer isformed on the third via. A fourth via is formed overlapping the thirdvia and surrounded by a fourth protective layer in the second ILD layerover the third metal layer. A controlled device is formed on the fourthvia, the controlled device is at the same height level as the secondmetal layer and controlled by the transistor. In one or more of theforegoing or following embodiments, the first via and the second viahave the same area in a plan view. In one or more of the foregoing orfollowing embodiments, the first and second protective layers are formedof titanium nitride or tantalum nitride. In one or more of the foregoingor following embodiments, the first metal layer connects to acontrolling device (400 a) which controls an applied voltage to thefirst metal layer. In one or more of the foregoing or followingembodiments, the second metal layer connects to a controlling device(400 b) which controls an applied voltage to the second metal layer. Inone or more of the foregoing or following embodiments, the controlleddevice includes one of an organic light emitting diode device, a memoryand a transistor. In one or more of the foregoing or followingembodiments, the method further includes, between the first metal layerand the second via, alternately forming a plurality of vias and metallayers, and all the plurality of vias have the same shape (or area) andall the plurality of metal layers have the same shape (or area), in planview.

The present application discloses an embodiment of a semiconductordevice. The semiconductor device includes a transistor having a sourceregion and a drain region. The transistor is formed on the substrate. Afirst via is disposed over the source region, and a first metal layerextends along a first direction on the first via. A second via overlapsthe first via over the first metal layer, and a second metal layerextends along a second direction different from the first direction onthe second via. A third via is at the same height level as the first viaover the drain region. A third metal layer is disposed on the third via.A fourth via overlaps the third via and over the third metal layer, anda controlled device is disposed on the fourth via. The device is at thesame height level as the second metal layer and is controlled by thetransistor. In one or more of the foregoing or following embodiments,the first via and the second via have the same area in a plan view. Inone or more of the foregoing or following embodiments, the first metallayer connects to a controlling device which controls an applied voltageto the first metal layer. In one or more of the foregoing or followingembodiments, the second metal layer connects to a controlling devicewhich controls an applied voltage to the second metal layer. In one ormore of the foregoing or following embodiments, the controlled deviceincludes one of an organic light emitting diode device, a memory and atransistor.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A semiconductor device, comprising: a transistoron a substrate, the transistor having a source region and a drainregion, wherein the source region includes: a first via formed over thesource region; a first metal layer formed on the first via, the firstmetal layer extending along a first direction; a second via formed overthe first metal layer, the second via overlapping the first via; and asecond metal layer formed on the second via, the second metal layerextending along a second direction different from the first direction,and wherein the drain region includes: a third via formed over the drainregion, the third via being at a same height level as the first via; athird metal layer formed on the third via; a fourth via formed over thethird metal layer, the fourth via overlapping the third via; and acontrolled device formed on the fourth via, the controlled device beingat a same height level as the second metal layer and controlled by thetransistor.
 2. The semiconductor device of claim 1, wherein the firstvia and the second via have the same area in a plan view.
 3. Thesemiconductor device of claim 1, wherein the first metal layer connectsto a controlling device which controls an applied voltage to the firstmetal layer.
 4. The semiconductor device of claim 1, wherein the secondmetal layer connects to a controlling device which controls an appliedvoltage to the second metal layer.
 5. The semiconductor device of claim1, wherein the controlled device includes one of an organic lightemitting diode device, a memory and a transistor.
 6. The device of claim1, further comprising: a plurality of vias and metal layers formedbetween the first metal layer and the second via.
 7. The device of claim6, wherein all the plurality of vias have a same shape (or area) and allthe plurality of metal layers have a same shape (or area), in plan view.8. A semiconductor device, the device comprising: a transistor over asubstrate, the transistor having a source region and a drain region,wherein the source region includes: a first via surrounded by a firstprotective layer in a first interlayer dielectric (ILD) layer on thesource region; a first metal layer formed on the first via, the firstmetal layer extending along a first direction; a second via surroundedby a second protective layer in a second ILD layer over the first metallayer, the second via overlapping the first via; and a second metallayer formed on the second via, the second metal layer extending along asecond direction different from the first direction, and wherein thedrain region includes: a third via surrounded by a third protectivelayer in the first ILD layer over the drain region, the third via beingat a same height level as the first via; a third metal layer formed onthe third via; a fourth via surrounded by a fourth protective layer inthe second ILD layer over the third metal layer, the fourth viaoverlapping the third via; and a controlled device disposed on thefourth via, the controlled device being at a same height level as thesecond metal layer and controlled by the transistor.
 9. The device ofclaim 8, wherein the first via and the second via have the same area ina plan view.
 10. The device of claim 8, wherein the first and secondprotective layers are formed of titanium nitride or tantalum nitride.11. The device of claim 8, wherein the first metal layer connects to acontrolling device which controls an applied voltage to the first metallayer.
 12. The device of claim 8, wherein the second metal layerconnects to a controlling device which controls an applied voltage tothe second metal layer.
 13. The device of claim 8, wherein thecontrolled device includes one of an organic light emitting diodedevice, a memory and a transistor.
 14. The device of claim 8, furthercomprising: a plurality of vias and metal layers formed between thefirst metal layer and the second via.
 15. The device of claim 14,wherein all the plurality of vias have a same shape and all theplurality of metal layers have a same shape, in plan view.
 16. Asemiconductor device, the device comprising: a transistor on asubstrate, the transistor having a source region and a drain region 140;a member including: an interlayer dielectric layer; a source-side via inthe interlayer dielectric layer formed over the source region and adrain-side via in the interlayer dielectric layer over the drain region;and a source-side metal layer in contact with the source-side via and adrain-side metal layer in contact with the source-side via, and acontrolled device on one of an uppermost source-side via and anuppermost drain-side via formed with the member stacked, wherein asecond interlayer dielectric layer in contact with the drain-side metallayer is made of a second semiconductor material different from a firstsemiconductor material of a first interlayer dielectric layer in contactwith the drain-side via.
 17. The device of claim 16, wherein: thecontrolled device is formed on the uppermost drain-side via, and atleast one of source-side metal layers is coupled to a logic device. 18.The device of claim 17, wherein none of drain-side metal layers iscoupled to the logic device.
 19. The device of claim 16, wherein thecontrolled device is a memory cell.
 20. The device of claim 19, whereinthe memory cell is one of a phase change memory cell and a resistancechange memory cell.